SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3122ad61346668cb54713819c688b4f86a266c47291f3972b246009c6d0a6ac9' 
  AND token = 'wTitMcTpqjNlKsgGxbtQeOO7HY0oEGxWseLYZb55DhQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}